This invention relates generally to roll neck bearing assemblies for rolls in rolling mills.
A well known example of this type of bearing assembly includes as an integral component a mechanical means for axially forcing the bearing assembly into and out of its operative position on the roll neck. The force exerting means consists of a nut mounted on an externally threaded ring. A separable subassembly consisting of a combination clamp ring and key is employed to detachably secure the threaded ring in a non-rotatable axially confined position on the roll neck. The nut is rotatable relative to the axially confined threaded ring and is engageable with other bearing parts. In other similar arrangements, the clamp ring and key are separate components.
Although these types of bearing assemblies have received worldwide acceptance throughout the rolling mill industry, experience has indicated that the clamp rings and keys sometimes present difficulties to maintenance personnel. More particularly, the clamp rings consist of two semi- circular pivotally interconnected ring segments. The key is received in mating keyways in the threaded ring and roll neck to rotatably fix the former relative to the latter. The ring segments are pivotally seated in a circular groove in the roll neck to provide an abutment cooperating with a shoulder on the roll neck to axially confine the threaded ring.
With large bearings, these clamp rings can weigh hundreds of pounds, thus requiring the need of a crane or other lifting device to install or remove them during the mounting or demounting procedures. Furthermore, depending on the orientation of the roll neck and bearing assembly, the semi-circular ring segments may at times exhibit a tendency to pivotally open under their own weight as the bearing assembly is in the process of being mounted on or removed from the roll neck. Mishaps can occur unless proper precautions are taken by maintenance personnel to prevent this from happening. Also, when separated from the roll neck and bearing assembly, the clamp ring and key subassembly can be damaged by mishandling, and it is also vulnerable to being contaminated by dirt, mill scale, etc. This further complicates the task of maintenance personnel.
In another known type of rolling mill roll neck bearing assembly; the integral force exerting means consists of a hydraulically actuated piston-cylinder unit cooperating in conjunction with a manually rotatable locknut. The force exerting means is detachably secured to the roll neck by means of a bayonet-type connection. Such bearing assemblies are prohibitively expensive because of their more complicated design, which includes a greater number of precision machined components. Moreover, the mounting and demounting of such bearing assemblies requires separate hydraulic pump/reservoir units, which further adds to overall costs. Also, the operating costs of such bearing assemblies is increased by the need to maintain hydraulic seals, pumps etc. In addition, the procedures involved in mounting and demounting such bearing assemblies are complicated, due in part to the need for precise positioning and alignment of the bayonet components prior to mounting and demounting.
Still another known type of roll neck bearing assembly employs a separate force exerting means which consists of a nut threaded on a ring, the latter being detachably connected to the roll neck by a bayonet-type mechanism. A number of difficulties are also associated with this type of arrangement. For example, the bayonet mechanism again lacks self alignment features, and thus considerable time and attention is required when coupling and uncoupling its components. Also, the bearing assembly and force exerting means are mounted on and removed from the roll neck separately from each other. This greatly complicates the tack of maintenance personnel, particularly since each such component requires the use of overhead cranes or the like.